Straightforward association of phosphate with giant reed fibers for rapid and efficient water decontamination

Lignocellulosics present attractive properties for sustainable water decontamination. Yet, they lack strong interactive functional groups, making their performance low compared to established adsorbents. Previous works generally focused on exhaustive chemical routes aiming at cellulose isolation from lignocellulosics and its functionalization to enhance its adsorption characteristics. Here, we show that the direct functionalization of Giant Reed (Arundo donax L) in benign Diammonium phosphate/urea system affords highly phosphorylated fibers at a high yield. The samples were characterized using SEM, XRD, FTIR, ¹³C and ³¹P NMR spectroscopies, conductometric titration, and Zeta-potential measurements to comprehend their morphology, chemistry, and surface properties. The chemical functionalization of Giant Reed (GR) leads to a significant amount of phosphates attached to the fibers, resulting in a charge content of 4.45 mmol·g^-1 and a negative surface charge in a wide pH range. Consequently, the adsorption performance of GR increased more than sixtyfold after phosphorylation, reaching adsorption capacities of 365 mg·g^-1 for copper ions and 606-1145 mg·g^-1 for dyes. Isotherm and kinetic adsorption models identified the mechanisms governing the adsorption process. This study reveals the prospects of a single-step benign chemical functionalization of a fast growing lignocellulosic resource (GR) that yields highly phosphorylated fibers for the removal of wastewater impurities.